Characterizations of urinary sediments precipitated after freezing and their effects on urinary protein and chemical analyses.

Author(s): Saetun P, Semangoen T, Thongboonkerd V

Publication: Am J Physiol Renal Physiol, 2009, Vol. 296, Page F1346-54

PubMed ID: 19339629 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   The purpose of this study was to determine the effects of storing centrifuged or uncentrifuged urine overnight at 4 or -20 degrees C on urinary sediment formation.

   Summary of Findings:

   In urine specimens stored overnight at 4 degrees C, no crystals were found. In contrast, storage of urine at -20 degrees C resulted in the formation of COD and amorphous crystals independently of specimen centrifugation. The authors state similar crystal formation was observed in specimens stored at -70 degrees C. SDS-page analysis revealed that urine proteins were significantly diminished in the sedimented specimens. MALDI-TOF mass spectrometry revealed a significant loss of stone modulating proteins and albumin in precipitated specimens. Further, sedimentation led to decreased urine calcium levels. The precipitates and proteins could be redissolved by vigorous shaking at room temperature. Also, 75% (p<0.001) of the sedimentation was prevented through the addition of EDTA.

   Biospecimens

   • Bodily Fluid - Urine

   Preservative Types

   • Frozen

   Diagnoses:

   • Normal

   Platform:

   Analyte	Technology Platform
   Morphology	Light microscopy
   Protein	MALDI-TOF MS
   Protein	1D/2D gels
   Electrolyte/Metal	Clinical chemistry/auto analyzer

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Storage temperature	-20 degrees C -70 degrees C 4 degrees C
   Storage	Storage duration	Overnight
   Storage	Storage conditions	Uncentrifuged Centrifuged
   Biospecimen Preservation	Fixative additive/buffer	EDTA

   View more

2. Study Purpose

   The purpose of this study was to determine the effects of pH on urinary sediment formation at -20 degrees C.

   Summary of Findings:

   In the normal urinary pH range of 5.8-6.6, the majority of crystals formed were COD; however, in specimens with lower or higher pH amorphous calcium crystals were preferentially crystallized. A slight reduction in urinary sediment formation was noted in specimens with a pH of 5.8 or 7.4.

   Biospecimens

   • Bodily Fluid - Urine

   Preservative Types

   • Frozen

   Diagnoses:

   • Normal

   Platform:

   Analyte	Technology Platform
   Morphology	Light microscopy

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Storage temperature	-20 degrees C
   Storage	Storage duration	Overnight
   Biospecimen Aliquots and Components	pH	5 5.8 6.6 7.4 8.2

   View more